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Suppose I have the following code:
class some_class{};
some_class some_function()
{
return some_class();
}
This seems to work pretty well and saves me the trouble of having to declare a variable just to make a return value. But I don't think I've ever seen this in any kind of tutorial or reference. Is this a compiler-specific thing (visual C++)? Or is this doing something wrong?
746
Constructors return an instance of a class, so they can't have any other return values.
A default constructor in Java is created by the compiler itself when the programmer doesn't create any constructor. The purpose of the default constructor is to initialize the attributes of the object with their default values.
A constructor cannot have a return type (not even a void return type). A common source of this error is a missing semicolon between the end of a class definition and the first constructor implementation. The compiler sees the class as a definition of the return type for the constructor function, and generates C2533.
A default constructor is a constructor that either has no parameters, or if it has parameters, all the parameters have default values. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameterless constructor A::A() .
No this is perfectly valid. This will also be more efficient as the compiler is actually able to optimise away the temporary.
89
Returning objects from a function call is the "Factory" Design Pattern, and is used extensively.
However, you will want to be careful whether you return objects, or pointers to objects. The former of these will introduce you to copy constructors / assignment operators, which can be a pain.
5
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